[PATCH 4/4] kthreads: allow cloning threads with different flags

J. Bruce Fields
2020-05-01T16:01:58Z

From: "J. Bruce Fields" <bfields@redhat.com>

This is so knfsd can add CLONE_THREAD.

Signed-off-by: J. Bruce Fields <bfields@redhat.com>
---
include/linux/kthread.h | 3 ++-
kernel/kthread.c | 11 +++++++----
2 files changed, 9 insertions(+), 5 deletions(-)

diff --git a/include/linux/kthread.h b/include/linux/kthread.h
index a7ffdf96a3b2..7069feb6da65 100644
--- a/include/linux/kthread.h
+++ b/include/linux/kthread.h
@@ -10,11 +10,12 @@ struct kthread_group {
spinlock_t create_lock;
struct list_head create_list;
struct task_struct *task;
+ unsigned long flags;
};

extern struct kthread_group kthreadd_default;

-struct kthread_group *kthread_start_group(char *);
+struct kthread_group *kthread_start_group(unsigned long, char *);
void kthread_stop_group(struct kthread_group *);

struct task_struct *kthread_group_create_on_node(struct kthread_group *,
diff --git a/kernel/kthread.c b/kernel/kthread.c
index 5232f6f597b5..57f6687ecec7 100644
--- a/kernel/kthread.c
+++ b/kernel/kthread.c
@@ -29,6 +29,7 @@ struct kthread_group kthreadd_default = {
.name = "kthreadd",
.create_lock = __SPIN_LOCK_UNLOCKED(kthreadd_default.create_lock),
.create_list = LIST_HEAD_INIT(kthreadd_default.create_list),
+ .flags = CLONE_FS | CLONE_FILES | SIGCHLD,
};

void wake_kthreadd(struct kthread_group *kg)
@@ -36,7 +37,7 @@ void wake_kthreadd(struct kthread_group *kg)
wake_up_process(kg->task);
}

-struct kthread_group *kthread_start_group(char *name)
+struct kthread_group *kthread_start_group(unsigned long flags, char *name)
{
struct kthread_group *new;
struct task_struct *task;
@@ -47,6 +48,7 @@ struct kthread_group *kthread_start_group(char *name)
spin_lock_init(&new->create_lock);
INIT_LIST_HEAD(&new->create_list);
new->name = name;
+ new->flags = flags;
task = kthread_run(kthreadd, new, name);
if (IS_ERR(task)) {
kfree(new);
@@ -314,7 +316,8 @@ int tsk_fork_get_node(struct task_struct *tsk)
return NUMA_NO_NODE;
}

-static void create_kthread(struct kthread_create_info *create)
+static void create_kthread(struct kthread_create_info *create,
+ unsigned long flags)
{
int pid;

@@ -322,7 +325,7 @@ static void create_kthread(struct kthread_create_info *create)
current->pref_node_fork = create->node;
#endif
/* We want our own signal handler (we take no signals by default). */
- pid = kernel_thread(kthread, create, CLONE_FS | CLONE_FILES | SIGCHLD);
+ pid = kernel_thread(kthread, create, flags);
if (pid < 0) {
/* If user was SIGKILLed, I release the structure. */
struct completion *done = xchg(&create->done, NULL);
@@ -645,7 +648,7 @@ void kthread_do_work(struct kthread_group *kg)
list_del_init(&create->list);
spin_unlock(&kg->create_lock);

- create_kthread(create);
+ create_kthread(create, kg->flags);

spin_lock(&kg->create_lock);
}
--
2.26.2